The Tektronix 10A1 is a differential amplifier plug-in for 647 scopes.
The input amplifier uses 8056 nuvistor triodes for the input cathode followers.
The 10A1 is a comparator, meaning that it has a built-in precision variable DC voltage source
that can be added or subtracted from the signal voltage.

Specifications

Maximum calibrated sensitivity: 1 mV/div

Minimum calibrated sensitivity: 20 V/div

Input impedance: 1 MΩ in parallel with 20 pF

Frequency response is DC to 45 MHz, except in maximum sensitivity setting, where it is 35 MHz